add missing cstdint includes (#7586)

src/deprecation.hpp

@@ -14,6 +14,7 @@
 
 #pragma once
 
+#include <cstdint>
 #include <string>
 
 /** See https://wiki.wesnoth.org/CompatibilityStandards for more info. */

src/serialization/base64.hpp

@@ -15,6 +15,7 @@
 
 #pragma once
 
+#include <cstdint>
 #include <string_view>
 #include <vector>
 

src/serialization/preprocessor.hpp

@@ -21,6 +21,7 @@
 #include "filesystem.hpp"
 #include "game_version.hpp"
 #include <optional>
+#include <cstdint>
 
 #include <iosfwd>
 #include <map>